JPS5843567B2 - Announcement of annual convalescent care examination - Google Patents

Description

Detailed Description of the Invention The present invention relates to an internal combustion engine, particularly a diesel engine,
The present invention relates to a supercharged internal combustion engine (power plant) equipped with a supercharging system.

A power plant having a supercharging system with a compressor and a turbine, and a bypass passage connecting the compressor and the turbine and constantly supplying the supercharged air from the compressor to an auxiliary combustion chamber arranged upstream of the turbine, is already known (French Patent A 70' 25074). This auxiliary combustion chamber has a fuel injection device and a number of openings formed in its wall, into which flows a combustion maintaining gas consisting of only the bypass air, or a mixture of the bypass air and exhaust gas from the engine, or the bypass air and exhaust gas supplied at the same time.

In such power plants, the flow rate of fuel injected into the auxiliary combustion chamber varies over a wide range depending on (eg, inversely proportional to) the operating speed of the internal combustion engine.

For example, the auxiliary combustion chamber operates at full power (maximum fuel flow rate) under certain conditions when the internal combustion engine is idling.
On the other hand, when the internal combustion engine is under load, the power is reduced (
It operates in the "pilot state."

In this load state, the auxiliary combustion chamber does not stop working, but continues to operate in the pilot state (pilot-state) to make the next reignition unnecessary.
The patient must continue to undergo treatment under normal conditions.

When the auxiliary combustion chamber is operated in such a pilot condition, the fuel flow rate introduced is very low, possibly down to about 2% or less of the injection flow rate during maximum power operation.

Therefore, the problem is that the fuel flow rate varies over a wide range, i.e. 1 to 50
The present invention aims to provide an auxiliary combustion chamber, particularly a fuel injection device, which can be changed within a range corresponding to a ratio of 1:60 in some cases.

It should be noted, in passing, that the operation of such an auxiliary combustion chamber is very different from that of an internal combustion engine of a gas turbine power plant.

That is, the thermal power of an internal combustion engine is an increasing function of the power provided by the internal combustion engine, whereas in the auxiliary combustion chamber described above, it is a decreasing function of the power, and the fuel flow rate is maximum when the internal combustion engine is idling.

Injectors are known which inject liquid fuel at sufficient high pressure into an auxiliary combustion chamber through a calibrated orifice of small cross-sectional area.

However, the similarity laws that allow the determination of the diameter of such an injector are not applicable to extremely low flow rates.

The diameters of the orifices capable of injecting such extremely small flow rates (eg, a few liters per hour) are equal to or less than the filtration limit, which of course often results in clogging of the bores of these orifices.

Furthermore, if the fuel alone must be compressed and injected into the auxiliary combustion chamber, the injection pressure in the orifice changes approximately in proportion to the square of the injected flow rate.

For example, if the injection flow rate varies within a range of 1 to 60, the pressure required for accurate injection varies from 1 to 360.
The rate changes to 0.

Apart from these pressure change concerns, in order to achieve proper injection over the full range of engine speeds, it is necessary to size the orifice taking into account minimum flow rates and fuel supply pressures as well.

In other words, below that level, the liquid is not sprayed in a mist form and dripping tends to occur.

As an example, for a supercharged diesel engine of about 3000 horsepower, the minimum fuel flow rate to maintain pilot condition in the auxiliary combustion chamber is about 2 liters per hour.

To achieve pressurized injection at this flow rate, it must be injected at a relative pressure of 0.8 bar (with respect to the pressure in the auxiliary combustion chamber).

The maximum fuel flow rate required to start the turbo compressor unit of an internal combustion engine and to operate the engine at idling speed reaches approximately 1201 J/hr.

This flow rate would then have to be injected at a relative pressure of 3000 bar, a condition that is clearly unacceptable.

Further, again using the above example, the size of the orifice through which the fuel is to be introduced corresponds to a diameter of 0.2 mm.

Such orifices have a great potential for clogging with impurities and for contamination with combustion residues.

In order to avoid the above-mentioned drawbacks, various solutions have been proposed in the past for injecting fuel into the auxiliary combustion chamber, in particular by pressurizing the fuel through a number of orifices which are activated in sequence according to the fuel injection flow rate.

However, such a solution is rather complicated and has a low ability to follow continuous changes in the flow rate of fuel injected into the auxiliary combustion chamber.

It is an object of the present invention to provide a supercharged internal combustion engine which overcomes the above-mentioned problems by eliminating the need for small diameter orifices, thereby preventing excessive fuel supply pressure rise at high flow rates, and by providing satisfactory injection atomization over the entire fuel flow rate without the need to operate a variable number of orifices.

For this purpose, the present invention provides an auxiliary combustion chamber with air/exhaust gas introduction means and a fuel injection atomizer for maintaining a supercharged internal combustion engine, the supercharged internal combustion engine comprising a turbo compressor with a compressor and a turbine,
This compressor is connected to a turbine, and is provided with a bypass passage for allowing supercharged air to flow into the turbine, and an auxiliary combustion chamber disposed upstream of the turbine, and has the following features.

The fuel injection spray device (a) opens into the auxiliary combustion chamber,
The fuel is supplied from a fuel pressurizing supply device that supplies fuel at a pressure that can be changed between a maximum flow rate and a minimum flow rate,
At least one injection port having a cross-sectional area (dimension) that can mechanically perform pressurized injection (in a mist) at a maximum flow rate corresponding to the maximum power of the auxiliary combustion chamber, but cannot perform pressurized injection in a mist at a minimum flow rate, and (b) at least one blower nozzle (fuel spray control port) that opens into the auxiliary combustion chamber near the injection port, where air from the compressor is constantly supplied via an air supply passage, and which controls atomization of the fuel by a jet of supercharged air from the air supply passage when the fuel flow rate is low, i.e., when pressurized injection is not performed correctly.

It will be appreciated that in such an auxiliary combustion chamber the fuel injection atomizer allows the following operation:

(i) Maximum operation: The fuel is pressurized and injected from the injection port by a medium pressure (e.g., several tens of bar) pump, while the air flow supplied through the blowing nozzle has no effect on the pressurized injection.

(b) Intermediate operation: The fuel is gradually subjected to the influence of the air flow from the blowing nozzle and is pressurized and sprayed by the action of air.

(c) Pilot State Operation Fuel is atomized by the action of the airflow from the blowing nozzle.

In this case, the air flow rate from these blower nozzles is sufficient by itself to ensure complete and stable combustion of the minimum flow rate of fuel corresponding to this pilot state operation.

The present invention also enables the following actions.

(a) Three conventional zones: the main combustion zone, the intermediate combustion zone,
and pressurized injection and complete combustion at maximum fuel flow rate in the auxiliary combustion chamber by arranging a dilution zone along the auxiliary combustion chamber.

(b) Aerobic atomization (i.e., fuel jet interaction with air jets) at minimum fuel flow (pilot flow) in the auxiliary combustion chamber and complete combustion of the atomized fuel in the air provided for the atomization.

In this case, the air is in sufficient quantity to provide optimal mixing with the fuel.

Here, the optimum mixture is a mixture close to the stoichiometric ratio that allows complete and stable combustion during pilot combustion without sonic disturbances of the internal combustion engine (which disturbances occur during sudden speed changes in the internal combustion engine).

Thus, the pilot combustion provides an immediate transition from pilot to full power in the auxiliary combustion chamber.

(c) Continuous variation of fuel flow between its maximum and minimum values, and transition between full power and pilot conditions while maintaining accurate, complete and stable combustion of injected fuel flow.

This transition is made possible by the fact that the supply of air which pneumatically atomizes the minimum flow rate of fuel is kept constant.

Thus, the power of the pressurized jet gradually decreases as the power of the aerobic atomization becomes dominant.

The present invention further provides the following advantages:

By constantly cooling the injector in which the nozzle orifice is formed, accumulation of tar and coke in the vicinity of said nozzle is avoided.

The airflow supplied through the blower nozzle removes the accumulation of soot and impurities near the nozzle, keeping the nozzle always clean.

Because the diameter of the nozzle is determined with respect to the maximum fuel flow rate, the likelihood of the nozzle accidentally becoming clogged is significantly reduced.

In fact, the blower nozzle is constantly supplied with boosted air and therefore there is no risk of it becoming contaminated or clogged.

The air supplied to each of the blowing nozzles of the injectors is advantageously made from supercharged air from the internal combustion engine, and this supercharged air is drawn in at a point in the supercharging system where the pressure is sufficiently high (higher than the pressure in the auxiliary combustion chamber), so that the flow rate of the airflow supplied to each of the blowing nozzles is sufficient, and thus the aerodynamic atomization of the fuel during pilot-ignition operation can be ensured.

This air is conveniently drawn downstream of a cooler located before the intake of the internal combustion engine.

To obtain maximum efficiency in the airflow supplied to each of these blower nozzles, it is advantageous to position each blower nozzle approximately perpendicular to the axis of the nozzle orifice.

To further enhance this efficiency, the blower nozzles are oriented tangentially to the circular jet orifice, providing an appropriate angle to the jet spray cone, which increases turbulence within the combustion zone and therefore contributes to improved flame stability when operating under pilot-fire conditions in the auxiliary combustion chamber.

The invention will be better understood from the following description of an embodiment thereof, given by way of example.

FIG. 1 shows a supercharged internal combustion engine equipped with a diesel engine 1 and a supercharging system.

The turbocharging system includes a single compressor 2 which is driven in rotation by a single turbine 3 .

However, it will be apparent that several of these may be ganged together, forming a multi-stage compressor or turbine.

The supercharged air discharged from the compressor 2 flows through a cooler 4 to the diesel engine 1 on the one hand, and flows through a bypass passage 6 to an auxiliary combustion chamber 5 on the other hand.

The bypass passage 6 is always open and has a sufficient cross-sectional area so that air which is supplied from the compressor and is not consumed by the internal combustion engine can be introduced into the auxiliary combustion chamber without pressure loss.

The auxiliary combustion chamber 5 receives supercharged air from the compressor 2, liquid fuel through a fuel injection spray device 12, and the diesel engine 1
It receives the exhaust gas flowing through the passage 33 from the exhaust port 31.

The outlet of this auxiliary combustion chamber is connected to a turbine 3 into which the exhaust gas from the diesel engine 1 and the combustion gas from the auxiliary combustion chamber 5 thus flow.

In the embodiment shown in FIG. 1, the supercharged air arriving at the auxiliary combustion chamber is divided by a regulating device 7 of the type described in French Patent Application No. 7310041 into primary air 8 which is led to the main combustion zone 9 of the auxiliary combustion chamber 5, and into secondary air 10 which is led to the dilution zone 11 of the auxiliary combustion chamber 5.

The dilution zone 11 is located downstream of the main combustion zone 9 .

The exhaust gas from the passage 33 is
The structure is similar to that described in Japanese Patent Publication No. 35653 of 1976, and the water flows into the dilution zone 11 through an opening 11a.

Before describing the fuel injection spray device 12 in the main combustion zone of the auxiliary combustion chamber 5 bordering the flame tube 17, reference is made to the graph of FIG. 4, which shows the variation in the flow rate (in n/h) of fuel Q injected into the auxiliary combustion chamber of an exemplary supercharged internal combustion engine as a function of the supercharging pressure P (in units of bar).

While the internal combustion engine 1 is stopped and before the supercharging system is started and the supercharging pressure supplied by the supercharging system reaches 2 bar, the auxiliary combustion chamber is operated at a maximum fuel flow rate (120 A?/h
) will be supplied.

At this point the engine is running and the energy imparted to the turbine by the exhaust gases increases as the engine power increases from 0 to approximately 20-30% of maximum power.

As a result, when the pressure of 2 bar increases to 3 bar, the fuel flow rate supplied to the auxiliary combustion chamber becomes 120/
h to about 21/h.

The auxiliary combustion chamber then goes into pilot operation with a boost pressure P of 3 bar and is supplied with a minimum fuel flow (2 liters/h).

Thus, the fuel flow rate is permitted to vary within a 1:60 ratio.

The fuel injection/spray device 12 is provided to ensure sufficient injection/spray over the entire flow rate, and mainly includes a fuel injector, which will be described below, and a blower means for controlling fuel spray, which is designed to spray fuel at low flow rates.

It is important to note that this blowing means has nothing to do with the combustion air supply device required to obtain the high thermal power of the auxiliary combustion chamber and dilution gas, and serves a completely different role as described below.

In the illustrated embodiment, a single fuel injection port 13 is provided in the flame tube 17.
The fuel injection port 13 is formed on the axis of the injector 24 .

Fuel is supplied to the injector 24 through a passage 32 from a fuel pressurizing supply device having a pump 14 whose supply amount is adjustable.

The circular nozzle 13 has a cross-sectional dimension selected to satisfy the following conditions: (a) it has a diameter small enough to pressurize and inject fuel at medium pressure (several tens of bar) when the maximum flow rate of fuel is introduced through the nozzle into the auxiliary combustion chamber, and (b) it has a diameter larger than the diameter required to maintain pressurized injection in the form of a mist even when the fuel flow rate is at a minimum.

Obviously, the fuel pressurization system 14 must be capable of supplying fuel at a pressure sufficient to cause maximum flow rate to be ejected through the nozzles into the auxiliary combustion chamber when maximum flow rate is required.

Clearly, this pressure is much lower than would be obtained if the orifice had a diameter small enough to sustain a pressurized jet at low flow rates.

By satisfying these two conditions, the maximum and minimum values of the cross-sectional area of the injection port are actually determined.

Within this fixed range, the value of the cross-sectional area is determined by the pressure that the pump available can provide and must be above the fuel filtration limit.

Also, the injection port 13 is generally arranged to inject and spray the fuel into a hollow cone of 60' to 90 degrees depending on the environment.

The internal geometry of such nozzle orifices 13 allows for rotation of the fuel (a feature known per se) in a centrally heated injector such as that sold by Danfoss (DANFO 8S).

The blowing means comprises at least one blowing nozzle 1 through which air is constantly supplied at a pressure higher than that existing in the auxiliary combustion chamber 5.
It has 5.

In this embodiment, a plurality of blowing nozzles 15 are provided (FIGS. 2 and 3).

These blower nozzles 15 each open near the nozzle port 13 into the auxiliary combustion chamber 5 and are oriented in such a direction as to supply an air jet at a substantially right angle to the axis of the injector 24 .

These nozzles are connected to an air supply system and arranged as follows:

That is, the air jet is constructed to have a velocity and supply that can pneumatically atomize fuel at low to minimum flow rates where the nozzle cannot perform pressurized injection.

Additionally, the air flow rate is selected to ensure complete combustion of the fuel when the fuel flow rate is at or near minimum.

Returning to the embodiment of Figs. 2 and 3, the blowing means of this embodiment has a cylindrical space 27 as an air chamber provided around the central inductor 24 via the passage 18 and coaxially with the inductor. This space 27 is axially spaced from the central opening 2.
The front side of the injection port is closed by a circular plate 25 through which the nozzle 6 is inserted.

The central opening 26 has a diameter larger than the diameter of the nozzle 13 and large enough so that the air jet does not interfere with the walls of the opening when sprayed under pressure.

The circular plate 3 is also supported on the conical front surface of the injector 24.

The blower nozzles 15 are each formed by a groove machined on one surface of a circular plate 25 .

The blowing nozzle 15 is advantageously oriented tangentially to the circumference of the jet 13 as shown in FIG.

Thus, the efficiency of the airflow delivered through the blower nozzles 15 is increased improving turbulence within the combustion zone.

In particular, during "pneumatic atomization" operation, the flame stability is improved due to the centrifugal action of the air-fuel mixture.

This centrifugal action gives an appropriate value to the angle of the spray cone when spraying by air action, as will be described later.

The air supplied to the blower nozzle 15 of the injection spray device 12 is advantageously supercharged air from an internal combustion engine.

In the illustrated example, the passage 18 connects the blower nozzle 15 to a portion immediately after the supercharged air passes through the cooler 4 , that is, immediately before the intake port to the internal combustion engine 1 .

This compressed (supercharged) cooling air is passed through passage 19 to act on air member 20 (FIG. 1) to couple pump 14 and injection/spray device 1 to each other.
2. A valve 21 mounted between the valve 21 and the outlet port 2 can be operated.

The air member 20 automatically removes fuel from within the injector atomizer 12 as soon as the fuel supply is stopped.

Therefore, when the fuel supply to the auxiliary combustion chamber is stopped and the internal combustion engine continues to operate thereafter, deterioration of the fuel remaining in the supply passage (such as coking or tarring) is avoided.

Additionally, the system of FIG. 1 includes an electric valve 22 upstream of the air member 20 which is actuated by ignition of the auxiliary combustion chamber 5 and which is controlled by a thermally responsive element 23 disposed within the combustion zone 9.

This thermally responsive element 23 blocks the intake of fuel in the event of accidental misfire in the auxiliary combustion chamber 5 .

This control may be manual, in which case the combustion in the auxiliary combustion chamber can be deliberately shut off.

The regulator 7 has the role of automatically regulating the pressure difference generated by the supercharged air flowing from the compressor 2 to the auxiliary combustion chamber 5 through the bypass passage 6 and of distributing this supercharged air into primary air and secondary air, and its configuration is similar to that described in French patent application No. 73 10041, as shown in FIG. 1.

This adjustment device 7 may, for example, be arranged such that the secondary air 10 crosses the adjustment device 7 and the cross-sectional area of the passage is variable, and a pressure difference Δp , which is an increasing function (preferably approximately linear) of the pressure P present in the upstream part of the bypass passage 6 between the upstream side of the bypass passage 6 connected to the compressor 2 and the downstream side connected to the auxiliary combustion chamber 5, is
and a second throttling device 35, the passage cross-sectional area of which can be automatically changed in accordance with the pressure difference Δp and which, upon being traversed by the primary air 8, gives to the primary air 8 a passage cross-sectional area determined by the pressure P-Δp in accordance with a certain predetermined relationship.

In this embodiment, the first throttle device 34 is constituted by a combination of an annular throttle valve 37 provided in a cylinder 36 and a conical wall of the casing 3B.

In this case, if the area of the portion surrounded by the outer periphery of the annular throttle valve 37 is S1 and the area of the bottom 41 of the slide 40 is S, the areas of the left and right walls of the throttle valve 37 are respectively (S-
s).

Here, if the output pressure (supercharging pressure) of the compressor 2, i.e., the pressure on the left wall side of the throttle valve 37, is P, and the pressure difference generated by the first throttle device 34 is Δp (i.e., the pressure on the right wall side of the throttle valve 37 is (P-Δp)), then:
The throttle valve 37 is provided with a leftward flow of Δp(S-s)...
A force of - (1) is applied.

On the other hand, the pressure on the right wall side of the bottom 41 is (P-Δp) (because there is no other throttle device between the right side of the throttle valve 3T and the right side of the bottom 41), so the pressure in the left direction at the bottom 41 is (P-Δp)s ... (2
) is applied.

(However, in this case, the atmospheric pressure on the left side of the bottom 41 is ignored for convenience.

) This leftward force is transmitted to the cylinder 36 via the spring 42, so that the throttle valve 37 moves in the direction of the arrow (1) above.
The system is stable at the point where the forces in equations (2) are balanced.

That is, △p(S-s)=(P-△p)s △pS=Ps △p=Ps/S...
(3) holds.

As is clear from the formula (3), the first throttling device 34
The pressure difference Δp generated by is proportional to the boost pressure P.

The second throttle device 35 is constituted by a plurality of holes 39 formed in the cylinder 36 and a tubular slide 40 having other holes which slides within the cylinder and changes the cross section of the openings of the holes 39.

This slide 40 has a bottom 41 which forms a piston.

The piston is subjected to two opposing forces.

That is, one is the compression force of the spring 42 (the force of which moves the slide in a direction so as to open the hole 39), and the other is a force which depends on the pressure P-.DELTA.p present downstream of the hole 39.

In this case, the relative position of the slide 40 with respect to the cylinder 36 (
That is, the cross-sectional area of the throttle device is
The force V 1 applied to the bottom 41 in the leftward direction, i.e., the force shown in equation (2), is determined by the equilibrium point between the force V 1 applied to the bottom 41 in the leftward direction by the spring 42 .

Here, the force generated by the spring 42 is the cylinder 3 of the slide 40.
Since the cross-sectional area is proportional to the amount of leftward displacement relative to 6, the cross-sectional area is ultimately proportional to (P-.DELTA.p).

Thus, the boost air reaching the regulator 7 through the bypass passage 6 is automatically divided into primary air 8 and secondary air 10, the ratio of which is determined by the normal cross-sectional area provided for the primary air.

Under these conditions, when the auxiliary combustion chamber 5 is operated at full power, the fuel flow rate is sufficient to produce a pressurized spray of fuel, but it is understood that the boost pressure P is relatively low.

As a result, the pressure of the air supplied to the blower nozzle is hardly ever higher than the pressure in the auxiliary combustion chamber.

On the other hand, when the auxiliary combustion chamber 5 is piloted, the boost pressure P increases as does the pressure difference Δp provided by the regulating device 7, although the boost pressure obtained is sufficient due to the simple fact that the exhaust gases from the internal combustion engine 1 drive the turbine 3.

Under these conditions, the pressure difference between the boost pressure supplied to the blower nozzle and the pressure in the auxiliary combustion chamber increases significantly, reaching 5 to 20% of the boost pressure, and the corresponding air flow rate ensures aerobic atomization.

The number and cross-sectional area of the blower nozzles 15 are therefore sufficiently close to stoichiometric mixing conditions for complete and stable combustion of the air/fuel mixture adjacent the injector atomizer when operating at this speed.

Eight blower nozzles with a total cross-sectional area of 12 m4 and a diameter of 0.7 n
The auxiliary combustion chamber equipped with the injection atomizing device 12 having the orifice 13 works as follows.

(a) From 120 to 25 liters per hour: When fuel is pressurized and injected from the nozzle 13, the fuel pressure upstream of the nozzle 13 is 20 relative bar (per 120 liters per hour).
to 0.8 relative bar (per 25 litres per hour).

Under these operating conditions, the air velocity from the blower nozzle 15 does not have a significant effect on the injected fuel.

FIG. 5 illustrates the operating condition where combustion is achieved purely by pressurized mist injection.

Here, combustion is stabilized by holes 16 formed around the periphery of the main combustion zone 9 substantially at the intersection of the flame tubes 17 and the fuel cone.

(b) From 10 to 2 liters per hour: the fuel stream is pneumatically atomized under the influence of the air current passing through the blower nozzle 15.

Under these operating conditions, the velocity of the fuel passing through the fuel inlet 13 is negligible compared to the velocity of the air supplied from the blower nozzle 15.

FIG. 6 shows the combustion state with a purely pneumatic spray.

The fuel flow is very slow, and the internal fuel burns without using air from the holes 16, but with air supplied from the blower nozzle 15 of the injection spray device.

As can be seen from the above description, the jet stream is set so that the air-fuel mixture is sufficiently close to a perfect stable combustion mixture condition.

(c) From 25 to about 10 liters per hour: The fuel is pressurized and sprayed at the outlet of the nozzle 13 and blown through the blower nozzle 1.
It is sprayed by the airflow supplied from 5.

Under these operating conditions, the velocity of the pressurized fuel droplets is sufficiently low that the air velocity provided by the blower nozzle affects the droplets.

Such a dual injection atomization (mechanical and pneumatic) combustion mechanism is intermediate between the configurations illustrated in FIGS.

As the boost pressure is gradually reduced and we move from "air-acting injection atomization" to "dual injection atomization," the space occupied by the flame increases.

Once a significant amount of airflow begins to pass through holes 16, the flame has a tendency to "stick" to the periphery of the torus recirculation zone.

The dual-injection atomization is achieved by an opening 28 extending along the side wall of the auxiliary combustion chamber, which receives the primary air supply at the rear of the auxiliary combustion chamber.
It will be even more effective if a

Advantageously, this opening 28 lies, on the one hand, in a plane parallel to the axis of the combustion chamber and, on the other hand, extends along an axis which forms an angle with the axis of the combustion chamber.

In this way, it is possible to provide the main combustion zone of the auxiliary combustion chamber with a rotating gas layer parallel to the axis of the auxiliary combustion chamber.

This layer ensures cooling of the auxiliary combustion chamber side walls while avoiding soot build-up and coking during primarily mid-flow, triple-injection atomization operation.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a supercharged internal combustion engine of a diesel engine, the main components of which are shown diagrammatically; FIG. 2 is an enlarged view of a fuel injection spray device in an auxiliary combustion chamber; and FIG. 3 is a schematic diagram of the fuel injection spray device in the auxiliary combustion chamber along the line 1-
FIG. 4 is a graph showing the change in the fuel flow rate Q injected into the auxiliary combustion chamber as a function of the boost pressure P; FIG. 5 is a cross-sectional view of the auxiliary combustion chamber showing the combustion state when the auxiliary combustion chamber is in full power operation; and FIG. 6 is a cross-sectional view of the auxiliary combustion chamber showing the combustion state when the auxiliary combustion chamber is in pilot operation. 1... Diesel engine (internal combustion engine), 2...
Compressor, 3... Turbine, 5...
Auxiliary combustion chamber, 6... Bypass passage, 7...
...Adjusting device, 12...Fuel injection spray device,
13: injection port, 14: fuel pressurization supply device, 15: blower nozzle (fuel spray control port), 18: supercharged air supply passage.

Claims (1)

[Claims] 1. An internal combustion engine; a supercharging system comprising a compressor whose outlet side is connected to the intake port of the internal combustion engine and supplies supercharged air to the internal combustion engine, and a turbine whose inlet side is connected to the exhaust port of the internal combustion engine and drives the compressor; a bypass passage interposed between the outlet side of the compressor and the inlet side of the turbine, having a diameter sufficient to allow supercharged air not supplied to the internal combustion engine to pass through, and equipped with throttling means on the outlet side for generating a pressure difference which increases with the supercharging pressure of the output of the compressor regardless of the speed and load state of the internal combustion engine; and a bypass passage whose inlet side is connected to the throttling means in the bypass passage, located upstream of the turbine, and equipped with a fuel injection spray device therein. In a supercharged internal combustion engine having an auxiliary combustion chamber which receives supercharged air from the bypass passage and fuel from the fuel injection spray device even when the internal combustion engine is idling, thereby generating combustion gas, thereby rotating the turbine to drive the compressor, and supplying supercharged air to the internal combustion engine, the fuel injection spray device comprises: (a) a fuel injection port which opens into the auxiliary combustion chamber and has an aperture which allows the supplied fuel to be pressurized and sprayed in a mist state at a maximum flow rate but not at a minimum flow rate; (b) a fuel pressurizing and supplying means which pressurizes and supplies the fuel to the fuel injection port between the maximum flow rate and the minimum flow rate such that the fuel decreases as the output of the internal combustion engine or the supercharging pressure increases; and (c) a fuel spray control port which opens into the auxiliary combustion chamber in the vicinity of the injection port. and an air supply passage for delivering a portion of the supercharged air to the fuel spray control port, and for spraying fuel at the fuel injection port at a rate ranging from an intermediate flow rate to the minimum flow rate by the air jet generated at this time, the fuel not being pressurized and sprayed in a mist state.